Relay circuit



Nov. 8, 1938. H. NYQUIST 2,135,596

RELAY CIRCUIT Filed Feb. 27,' 1957 WML/WM Patented Nov. 8, 1938 n UNITED STATES PATENT OFFICE Telephone Laboratories,

Incorporated, New

York, N. Y., a corporation of New York Application February 27, 1937, Serial-No. 128,131

7 Claims.

This invention relates to a relay circuit and particularly to a telegraphreceiving relay circuit for use with a composite telephone and telegraph system.

An object of the invention is to prevent interference in the line due to operation of the receiving relay.

A more specific object of the invention is to neutralize the inductive effect upon the line windings of the relay, and therefore upon the line, of the sudden impulses occurring in the vibrating windings of the relay.

A still further object yof the invention is to neutralize the inductive effect upon the line windings of the relay, and therefore upon the line, of voltages induced in the windings of the relay by the movements of the armature. Inorder to improve the operation yof ktelegraph receiving relays, particularlyk when such relays are to be used over cable circuits operating on comparatively Weak currents, it is lusual to provide in connection with the relay a so-called vibrating circuit. This vibrating circuit ordinarily includes a winding on the relay, known as the vibrating Winding, as well as a resistancecapacitynetwork. The arrangement usually followed is such that, while 'the armature is in engagement with one contact, the eectof the vibrating circuit tends to move the armature from engagement with that contact and into engagement with the opposed contact. When the armature does leave the contact, due to the keffect of a current reversal in the line windings, there is a sudden accelerating force produced in the vibrating winding due to the charge on the condenser included in the vibrating circuit and, when the armature iirst engages with the new contact, there is a sudden force tending to hold it in engagement therewith thereby preventing so-called chatter.

It follows from the above, therefore, that the vibrating circuit functions by virtue of sending sudden impulses into the vibrating winding and applicant has observed that these impulses, due to the transformer action of the relay windings, cause similar impulses to be set up in the line windings of the relay and to be transmitted out over the line. While these impulses are vattenuated somewhat by composite sets and the like they do nevertheless, particularly in systems where the repeater gain is considerable, give rise to that particular type of interference commonly known by communication engineers as receiving end thump.

Applicant has observed also that thump re-r (CI. ITS-88) sults from voltages induced in the windings of the relay due to the movements of the armature.

In accordance with a particular feature of the invention means are provided whereby the inductive eiTect upon the line windings of impulses caused either by the functioning of the vibrating circuit or by the movements of the armature are neutralized so that zero voltage is produced in the line. f

In accordance with a specific embodiment of the invention a plurality of neutralizing windings are provided, one neutralizingwinding being connected in series with each section of the normal windingsfof the relay. Impulses similar to those occurring in the normal vibrating windings, occur also in the neutralizing windings connected in series therewith and, as the neutralizing windings are all in inductive relationship, these impulses cause by induction similar irnpulses in the neutralizing windings connected in series with the line windings. Now the poling of the neutralizing windings is opposite to'that of the relay windings so that, while the impulses set up in the neutralizing line windings are of equal intensity to those set up in the normal relay line windings, they are of opposite polarity, the result being that one neutralizes or cancels the other'and zero voltage results in the line.

In accordance with a modiiication of the invention an additional neutralizing winding is provided, being connected in series with the relay armature and with a resistance-capacity network. This winding acts to neutralize the voltages set up in the relay windings due to movement of the armature.

A complete understanding of the arrangement contemplated by the invention and appreciation of the desirable features thereof will be had by consideration of the following detailed description in connection with the annexed drawing in which:

Fig. 1 illustrates a telegraph receiving relay circuit including neutralizing windings of the nature contemplated by the invention; and

Fig. 2 illustrates a modification of the circuit in accordance with which an additional winding is provided in series with the armature.

Referring now to Fig. 1, a telegraph receiving relay Il as illustrated provided with a vibrating winding comprising equal sections I2 and I3 and two line windings comprising respectively equal sections I6 andy I1 and I8 and 2|. Armature 22 is vibrated bythe eiect of currents received over line 23 on the line lwindings of the relay and acts to transmit impulses of alternate polarity from positive battery 25 and negative battery 21 to the receiving or recording device 28. During transmitting, switch arm 5| is vibrated by means, not shown, (a relay for example) to transmit impulses of alternate polarity from positive battery 52 and negative battery 53 out over line 23. Due to the fact that network 55 closely simulates the line impedance at the essential telegraph frequencies and as the various sections of the line windings are all nicely balanced the magnetic eifect of the transmitted impulses upon the relay is negligible.

Six neutralizing windings 56, 51, 58, 6|, 62 and 63, are provided. Winding 53 is connected in series with one terminal of section i2 of the vibrating winding and resistance 66 while winding 6| is connected in series with one terminal of the other section I3 of the vibrating winding and condenser 61. The network is connected to ground 1| through resistance 12. Neutralization winding 51 is connected in series with one side of line 23 and one terminal of section I6 of one of the line windings of the relay; neutralizing winding 62 is connected in series with a terminal of section |1 of the same line winding and network 55. Neutralizing winding 56 is connected in series with the other side of line 23 and a terminal of section I8 of the other line winding of the relay; neutralizing winding 53 is connected in series with a terminal of section 2| of the same line winding and network 55.

The neutralizing windings simulate the winding arrangement of the relay in that the mutual inductance between either winding '58 or winding 8| and windings 56, 51, 62 or 63 is the same as the mutual inductance between either section I2 or section I3 of the vibrating winding and sections I5, l1, I8 or 2| of the line windings. The poling of the neutralizing windings, however, is opposite to that of the normal relay windings.

Assuming now that armature 22 has just been moved into engagement with contact 16 due to a current reversal in line 23, an impulse will be transmitted from negative battery 21 over lead 11 to receiving device 28, which may be a sounder, for example. There will also be a sudden flow of current from negative battery 21, over lead 18, through section I3 of the vibrating Winding and neutralizing coil 6| to condenser 61, this flow of current being effective to charge condenser 61. Substantially no current flows through section I2 of the vibrating winding at this instant as the resistance of the path through section I3 is much less. This ilow of current tends to hold armature 2| in engagement with contact 16. Upon condenser 51 reaching its full charge, however, the current then ilows through section I2 of the vibrating winding, neutralizing winding 58, resistances 66 and 12 to ground 1|, this iiow of current tending to cause armature 22 to move away from contact and into engagement with the opposed contact Il. Armature 22 remains in engagement with contact 16, however, due to the effect of the current flowing in the line windings of the relay.

Immediately upon armature 22 leaving contact 16, due to change of direction of the line current, condenser 61 starts to discharge and causes -a flow of current through both sections, |-3 and |2, of the vibrating winding, this ow of current tending to urge or accelerate armature 22 in its travel from contact 15 to contact IUI. As soon as armature 22 engages contact |0| an impulse from positive battery 26 'will be transmitted over lead 11 to receiver 28 and current will be transmitted over lead 18 'and through section I3 of the'vibrating winding and neutralizing winding 6| to charge condenser 61, this current being in a direction tending to urge armature 22 into engagement with contact IUI, thereby preventing "armature chatter. As before substantially no current ows at this instant through section I2 of the vibrating winding due to the greater resistance of this path. Upon condenser 61 becoming charged, however, current iiows through section |2 of the vibrating winding, neutralizing winding 58, resistances 66 and 12 to ground 1 I, this current tending to move armature 22 away from contact IUI and toward the opposed contact 16.

It will be apparent from the above that impulses or sudden spurts of currents in one direction or the yother are being set up almost continuously (that is, while the circuit is in use) in the vibrating winding and it has been observed, as stated above, that due to transformer action of the relay windings, similar impulses are set up in the line windings of the relay. These induced impulses, if unimpeded, are transmitted out over the line and give rise to so-called receiving end thump. In accordance with applicants arrangement, however, any impulses occurring in the vibrating Winding of the relay occur also in neutralizing windings 58 and 6| which are connected in series with sections I2 and I3 of the vibrating winding. Now the mutual inductance between either winding 58 or 5| and windings 55, 51, 52 or 63 is the same as the mutual inductance between either section I2 or I3 of the vibrating winding and sections I5, I1, |8 or 2| of the line windings from which it follows that, for any impulse induced in any ofthe sections of the line windings due to impulses occurring in either section of the vibrating winding, there will be an impulse of like magnitude induced in the corresponding neutralizing winding by the impulse occurring in winding 58 or 6|. Due to the fact, however, that the poling of the neutralizing windings is opposite to that of the relay windings, the impulses occurring in the neutralizing windings, while of equal magnitude to those occurring in the corresponding line windings, are of opposite polarity so that any impulses induced in the line windings are neutralized or canceled by the equal-magnitude oppositely-poled impulses occurring in the neutralizing windings. No interfering impulses occur in line 23 therefore.

In Fig. 2 a modincation of the arrangement is illustrated. In accordance with this modification, an additional neutralizing winding has been provided for preventing the origination in the line of interfering currents due to motion of the armature. Here, as in the instance of the arrangement just described, we have a telegraph receiv- Ing relay I provided with a vibrating winding comprising two balanced sections ||2 and 3 and two line windings comprising, respectively, sections ||6 and ||1 and sections ||B and |2|. Armature |22 is moved between contacts |23 and |26 due to the effect on the line windings of current reversals in line I 21. As the armature moves from one contact to the other, impulses of alternate polarity from positive battery |28 and negative battery |5| are transmitted over lead |52 to receiving device |53. During transmitting periods, switch arm |56 is vibrated by suitable means (not shown) and transmits impulses of alternate polarity from positive battery |51 and negative battery |58 over line |21. Neutralizing windings |6I, |62, |63, |66, |61 and |68 correspondrespectively in arrangement and function to neutralizing windings 56, 51, 58, 6|, 62 and 63 described above, while resistances |1| and |12 and con- 75 denser |13 of the vibrating circuit correspond respectively in arrangement and function to resistl ances 66 and 12 and condenser 61 ofthe vibrating circuit of Fig. l. In accordance with the modification illustratedin Fig. 2, however, an additional neutralizing winding |16 has beenprovided, being connected'in series with armature |22 and a network comprising resistance |11 and condenser Applicant has observed that when armature |22 is moving from contact |23 to |26 or vice versa a counterelectromotive force is set up in the relay windings and transmitted out over line |21 giving rise to thump. This force has been found to be approximately proportional to the velocity of the armature, building up rather gradually to a maximum as the armature moves from one contact to the other. When the armature engages the opposed contact and is brought to rest abruptly there is, of course, a sudden drop in the electromotive force. The suddenness of this change in voltage results'in a wave with high frequency components and audible thump. It is at this time, therefore, that-is upon engagement of the armature with a contact, that the eiect of the voltages' caused by armature motion is particularlytroublesome. By the provision of the neutralizing winding |16 and the associated network, applicant has provided means for substantially eliminating thump resulting from armature motion, the arrangement operating in the following manner.

Let us assume, by way of explanation, that armature |22 is being moved from engagement with contact |23 toward contact |26 due to a current reversal in line |21. Due to the motion of armature |22 and the reaction on the electrical circuit, a counterelectromotive force is generated in the windings of the relay which gradually builds up to a maximum as the armature approaches Contact |26. Now as the armature engages contact |26 it stops abruptly and there is, of course, a sudden drop in the electromotive force. The suddenness of this change in voltage results in a wave in the relay windings which, if unimpeded, would be transmitted out over line |21 causing thump, However, just as armature |22 engages contact |26, there is a sudden flow of current from negative battery |5| through neutralizing winding |16 and resistance |11, this current rising rapidly from zero to a maximum value determined 4by the magnitude of resistance |11 and the operating voltage. By properly xing the value of resistance |11 and condenser |18 it is possible to produce in neutralizing coil |16 a current Wave which is the substantial counterpart, both with respect to magnitude and timeconstant, of the interfering wave set up in the relay windings when the armature strikes contact |26. Similar waves are set up in the other neutralizing windings, due to the mutual induction between winding |16 and the other neutralizing windings, and, due to the opposite polarity of the neutralizing windings and the relay windings, these waves neutralize or cancel any interfering waves set up in the respectively associated relay windings.

While armature |22 rests in engagement with contact |26, condenser |18 charges so that the current through resistance |11 dies out before the next operation of the armature takes place.

While certain specific embodiments of the invention have been selected for illustration and detailed description, the invention is not of course limited in its application to these specific embodiments. The embodiments described should be' taken as illustrative of the invention and not as restrictive thereof.

` What is claimed is:

1v. A relay comprising an armature, opposing contacts adapted to be engaged by said armature, a main Winding forv operating said armaturebetweensaid contacts, an auxiliary winding normally tending to move the armature from the contact with which it is in engagement to the opposite contact, means effective upon disengagement-of said armature from either of said contacts for causing' a current impulse in said auxiliary winding effective to accelerate further movement of said armature, and means including'an inductive winding for neutralizing the inductive effect of said current impulses on said main winding.

2. A -relay comprising an armature, opposing contacts adapted to be engaged by said armature, amain winding for operating said armature between said contacts, .an auxiliary winding normally tending to move the armature from the contact with which it is in engagement to the opposite contact, means effective upon disengagementfof said armature from either of said contactsk for causing a current impulse in said auxiliary winding effective to accelerate further movement of rsaid armature, and means for neutralizing the inductive effect oi' said current impulses on said main winding, said last-mentioned means including a winding in series with said main winding and means for inducing therein impulses of equal intensity and opposite polarity to the impulses induced in said main winding by said impulses in said auxiliary winding.

3. A relay comprising an armature, opposing contacts adapted to be engaged by said armature, a main winding for operating said armature between s-aid contacts, an auxiliary winding normally tending to move the armature from the contact with which it is in engagement to the opposite Contact, means effective upon disengagement of said armature from either of said contacts for causing a current impulse in said auxiliary winding eifective to accelerate further movement of said armature, and means for neutralizing the inductive effect of said current impulses on said m-ain winding, said last-mentioned means' including a third winding in series with said auxiliary winding and a fourth winding in series with said main winding, said third and said fourth windings being in inductive relationship and said third winding and said main winding being oppositely poled.

4. A relay comprising an armature, opposing contacts adapted to be engaged by said armature, a potential source associated with each of said contacts, a winding for operating said armature between said contacts, and means for neutralizing the effect upon said winding of impulses induced in said Winding due to movement of said armature, said means including a second winding connected in series with said operating Winding and means for introducing in said second winding impulses which are the substantial counterpart of said impulses induced in said operating winding and which are of opposite polarity with respect thereto.

5. A relay comprising an armature, opposing contacts adapted to be engaged by said armature, a potential source associated with each of said contacts, a winding for operating said armature between said contacts, and means for neutralizing the effect upon said winding of impulses induced in said winding due to movement of said armature, said means including a second winding connected in series with said operating winding and means for introducing in said second Winding impulses which are the substantial counterpart of said impluses induced in said operating winding and which are of opposite polarity with respect thereto, said last-mentioned means including a third Winding connected in series with said armature and n inductive relationship to said second Winding.

6. A relay comprising an armature, opposing contacts adapted to be engaged by said armature, a potential source associated with each of said contacts, a winding for operating said armature between said contacts, and means for neutralizing the effect upon said winding of impulses induced in said winding due to movement of said armature, said means including a second Winding connected in series with said operating winding and means for introducing in said second winding impulses which are the substantial counterpart of said impulses induced in said operating winding and which are of opposite polarity with respect thereto, said last-mentioned means including a third winding in inductive relationship to said second winding, said third winding being connected in series with said armature whereby said third winding is effectively connected in series with a potential source upon engagement of said armature with either of said contacts and means connected in series with said third winding whereby the characteristics of the impulse produced therein upon engagement of said armature with either contact may be determined.

7. A relay comprising an armature, opposing contacts adapted to be engaged by said armature, a potential source associated with each of said contacts, a winding for operating said armature between said contacts, and means for neutralizing the effect upon said winding of impulses induced in said winding due to movement of said armature, said means including a second Winding connected in series with said operating winding and means for introducing in said second Winding impulses which are the substantial counterpart of said impulses induced in s-aid operating winding and which are of opposite polarity with respect thereto, said last-mentioned means including a third Winding in inductive relationship to said second winding, said third winding being connected in series with said armature whereby said third Winding is effectively connected in series with a potential source upon engagement of said armature with either of said contacts and a resistance-capacity network connected in series with said third winding whereby the character-- istics of the impulse produced therein upon engagement of said armature with either contact may be determined.

HARRY NYQUIST. 

